Hey,
I am finally looking into buying some studio monitors.
Of couse dub is very bass heavy so I guess it has special needs on monitors.
From what I've read, most quality monitors are only down to 40 or even 50 Hz, and I am a bit worried if that would be enough for dub, or if I would need to use a sub with them, which would exceed my price limit.
The ones that go below 40 Hz are supposed to not sound very good on mids and highs, so it's apparently always a trade-off.
I am currently looking at the Samson Rubicon R8A.
Do you think they would be a good choice?

If you're on a budget then KRK's are a great compromise between sound and cost. I've been usung a pair of passive 8" ones for the last 15 years and they're still going strong. Newer active models have a good 'weight' to the sound for their price. Excellent for dub mixes as the low end seems farily accurate. Would recommend you look at acoustic treatment/response in your listening area as well, as this is more important.

When your budget no longer holds you back listen to some of the higher-end Genelecs or, if you really want the ultimate, Barefoot MM27's